This typically occurs when a region has been included on the Itinerary and the previous Port is within that region. Therefore, there is no distance to travel between that Port and region as they are in the same location.
An example is the Port of Taboneo and the region of ‘Lowdraft - Java Sea’. ‘Lowdraft - Java Sea’ is an entire region and not a singular Port location. The Port of Taboneo is a Port within the region of ‘Lowdraft - Java Sea’. Therefore, the miles show correctly blank on the Itinerary:
